1. Field of the Invention
The present invention relates to a hydrated oxide powder comprising hydrated iron oxide as a main component which is used as a raw material for producing a magnetic recording medium having high quality.
2. Description of the Prior Arts
The quality required for a magnetic recording medium is to improve a coercive force suitable for high density recording and to minimize a particle size so as to improve SN ratio.
When the particle size is reduced, a sintering phenomenon is easily caused in a step of converting a hydrated iron oxide into magnetite or .gamma.-ferric oxide, whereby the coercive force is reduced and a dispersibility is inferior. In order to prevent such sintering phenomenon, it has been proposed to form a silicon compound on the surface of a hydrated iron oxide such as goethite, or to add a phosphate as a pretreatment so as to improve the dispersibility as disclosed in Japanese Unexamined Patent Publication No. 1,44,400/1977 and 129,198/1978.